Halinchondrin analogs have been disclosed as having anti-cancer and antimitotic activity (U.S. Pat. No. 6,214,865, incorporated herein by reference). In particular, Halichondrin B has been reported as a potent anticancer agent that was first isolated from the marine sponge Halichondria okadai (U.S. Pat. No. 6,214,865; WO 2005/118565 A1 and WO 2009/124237 A1, all incorporated herein by reference). In addition, Eribulin, a Halichondrin B analog, has been reported as having potent anticancer properties (WO 2009/124237 A1, incorporated herein by reference).
Halichondrin B
Eribulin Mesylate (where Ms=CH3SO2—)
The synthetic approach described (U.S. Pat. No. 6,214,865; WO 2009/124237 A1, Bioorg. Med. Chem. Lett., 2004, 14, 5551 and J. Am. Chem. Soc. 2009, 131, 15642, all incorporated herein by reference) involves introduction of nitrogen in the C27-C35 fragment of Eribulin after assembly of the macrocycle. Such an approach can add synthetic steps to the later stages of the synthesis, after the building blocks corresponding to the C1-C13 and C14-C26 fragments have been introduced. The synthesis of those fragments is long and complex; and every additional step in the synthesis can imply an increase in manufacturing costs. In addition, due to the cytotoxic nature of Eribulin, late introduction of the nitrogen results in a greater number of steps that can require special safety containment, which can limit throughput and can also increase the cost of producing the active pharmaceutical ingredient (API).
There is a need in the art for a compound that corresponds to the C27-C35 fragment, and that can be used in process for preparation of Halichondrin and its analogs, including Eribulin. In addition, there is a need in the art for a compound that can help to improve the convergence of the synthetic route for preparation of Halichondrin and its analogs, and therefore, can also help to reduce the amount of C1-C13 and C14-C26 fragments required. Further, there is a need in the art for a compound that can help to reduce the number of steps that can require safety containment for preparation of Halichondrin and its analogs. Moreover, there is a need in the art for a process for preparation of such a compound.